Guinea midfielder will join the Reds next summer in a deal that could eventually be worth €70m.

RB Leipzig sporting director Ralf Rangnick has claimed that the club's inability to offer an annual salary upwards of €10m (£8.9m, $11.7m) to Naby Keita was a key reason why they were unable to prevent the player from signing for Liverpool.

The Guinea international was linked with a big-money switch to Anfield throughout the most recent transfer window, with his chief suitors seeing club-record bids of £57m and £66m dismissed out of hand.

Liverpool did eventually succeed in their dogged pursuit of Keita, however, after agreeing to pay an undisclosed sum on top of the £48m release clause in his contract that was set to become active next summer. The highly-rated box-to-box midfielder will officially join up with Jurgen Klopp's side on 1 July 2018.

Keita has made quite an impression at Leipzig since joining from sister club Red Bull Salzburg in 2016. In his first season, he helped the Bundesliga debutants to qualify automatically for the group stages of the Champions League and finish as runners-up to reigning champions Bayern Munich.

Rangnick would have preferred to have retained the services of a player whom he refers to as "exceptionally talented" and one of the best he has worked with over the past two decades, although concedes that Leipzig's self-imposed €5m-a-year wage cap rendered that outcome very unlikely.

CEO Oliver Mintzlaff previously admitted that they would never have sold Keita if it were not for that release clause and stressed they did not expect another team to be willing to pay significantly more just a few months after it was first agreed.

"It would be ten times better for me to have him with us for another five years, but that is simply not possible," Rangnick told German sports magazine Kicker. "With us, it is just not possible to pay salaries in the double-digit million range."

Kicker claim that Liverpool will spend up to €70m (£62.7m) on Keita depending on various performance-related add-ons, a full €55m more than Leipzig paid Salzburg in June 2016. That initial sum is reportedly expected to grow by around €8m in bonus payments between now and next year.

Keita, recently sent off twice for club and country in the space of just three weeks, has scored 10 goals and provided nine assists in 41 appearances across all competitions for Leipzig since the start of 2016-17. Ralph Hassenhuttl's men currently sit third behind Borussia Dortmund and Bayern in the German top-flight and have taken four points from their first three Champions League matches against AS Monaco, Besiktas and FC Porto.

By contrast, defensively vulnerable Liverpool, thumped 4-1 by Tottenham Hotspur at Wembley Stadium on Sunday (22 October), lie ninth in the Premier League after winning only three of their opening nine games and conceding a hefty 16 goals. They top their Champions League group ahead of Spartak Moscow on goal difference after beating Slovenian champions Maribor 7-0 last week to record the biggest away win by an English team in the history of the European Cup.

Naby Keita will leave RB Leipzig for Liverpool in the summer of 2018Matthias Kern/Bongarts/Getty Images